TP52s

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evolution

 

Either 225-hp outboards have shrunk an awful lot, or that's one heck of a lot of beverages in that cooler, or you're screwing around with Photoshop again

 

2003

2003...

 

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Dear jorghenderson :

As the poster of the 2,000th message of this thread, you are hereby condemned to crew under Frank's tutelage for the following 12 months during which you are required to:

- Never talk bad about any MacGregor
- Never talk good about any breed of a TP-52
- Always post to this forum talking about East coast conspiracies to fill the west coast of TP garbage
- Talk about how good are the Mac 26 (whatever version) to train the new breed of sailors.
- Justify that a poorly fitting dagger board is really a "self tacking board"
- Promote the use of huge inboards/outboards as true sailing mechanisms

Frank: This guy is all yours...

 

My how we love the smell of boat design.net in the morning. It smells like stink pots. It smells like victory.

You may be referring to Perry's review and the Swiftsure.

I went looking for Bob Perry the other week but he may have moved his office to get away from me (hee hee) and the customers I have sent him. In any case Perry reviewed the Mac26 about a year or two ago and printed a story about a Mac26x owner who had a heart attach and I discussed that review and story with him a few years ago. The MacGregors are good sailboats and powerboats. They are not race boats but then neither are the TP52s. Both are race trainers.

Does any one really disagree? TP52s are bad for students but good for instructors because you can get one famous sailer aboard as instructor and spread the cost among 10 to 20 lubbers. MacGregors are kind boats - so instructors need not ride with the students and famous sailors can teach via shore parties and zodiacs.

Anyway it was Perry who identified the Mac 26x canard (what most call a centerboard) as a jibing board (also spelled gybing board). It is the jibing board that makes the Mac26x point better than any trailerable sailboat built prior to 2002. Later Perry was asked to justify that a poorly fitting dagger board is really a self tacking board by anarchists. They were to far below his level to comprehend. Not like the boat designers here

In 2002 the less advanced design, the Mac26m, was fitted with a self tacking rotating mast. So comparing the X model to the M model indicates that Roger Macgregor thinks few operator controls are really necessary on modern designs. The fins and mast can self adjust and do on his designs. The sails even self trim on the X but this is a TP52 thread.

A TP52 in the 2007 Swiftsure is reported to have had a heart attach victim, possibly the owner, during the race. The TP52 motor sailed by spinnaker to help, the victim was removed, and then I guess the race was finished.

My point is that an engine which can get you to help is a safety item. The TP52 could not have had enough engine power to get the boat to hull speed or why the spinnaker? TP52s have motors that are just to small. They are designed that way under the misconception that weight should be as low as possible. Hence smaller motors are used so the weight can go into the bulb.

When I race my Mac26x, I lift and then disconnect the motor from the helm. It then becomes ballast. Currently we lock it in a mid position because race rules do not allow us to move this form of solid ballast from side to side. But I think you can see how easy that would be. If we were racing minis across the atlantic where moving solid ballast from side to side is allowed... well this thread is about TP52s. There is much more to say about them.

Lets just hint that TP52s should have very little resale value. The current owners are stuck with lemons. More later

 

This should be the first statement of yours that actually makes any sense...

 

A 52-foot sailboat with a crew of 10 or 20 does not need to plane under engine. Doing 90% of hull speed under power is all such a craft needs. They are faster under sail because they have a gigantic sail plan, and wind is free (unlike diesel). If you were to put a 400 hp diesel in a TP52, it would be faster under engine, but then you're adding weight in the hull (not a very advantageous place) and taking up space for motor and fuel. And it wouldn't be the same sailboat anymore.
A 26-foot hybrid power/sail trailer boat capable of towing skiers has to be able to plane under engine, or nobody would buy it.
Remember, the TP52 is eight times the size of the Mac, and carries eight times the crew.

 

Uh...with the wind at Swiftsure last year, that TP52 was moving faster than your boat would move if you were trailering it down the freeway.

An engine would have just slowed them down.

 

Ballast, ballast, ballast. Nothing ruins an elliptical planform as quick as considering ballast.



Also as far as elliptical planforms go, have a look at glider design. Almost none to be seen despite the most cut-throat of competition - sometimes you see a radiused corner. The extreme aspect ratios reduce the induced drag to such an extent that an elliptical tip makes little sense. If it did ... they would be using it.

Also - this is reaching the limits of my understanding so maybe someone wiser can mop up the details or correct me - the thing that is needed is not an Elliptical planform but an elliptical PRESSURE spanwise distribution.

In a 2D case the easiest way on paper is an elliptical planform and a very close approximation is a straight untapered length starting at the root with a straight tapered end section. This is what most sailplanes use as in the picture above - you can see the break between the tapered and untapered sections about halfway along the span.

But as soon as you move to a 3D case there are other options. You can change the PRESSURE distribution with twist or lateral bend or by altering the camber in the head.

These sorts of subjects get quite interesting as you dig a bit deeper - it is very rewarding to assume that there is NO ideal planform or no ideal solution for any physical system. Look at the underlying reasons and dig deep and be sceptical of what is the accepted wisdom.

I remember how most used to think that Genoas were actually EFFICIENT!!!! Or that a rudder separate from the keelr would be impossible to engineer in a safe reliable way.

To be sceptical is one thing but it has to be based on some knowledge and be open to correction unlike Mighetto's raving in aid of maintaining his fixed point of view.

MIK

Hey, look, I'm hijacking Mighettos thread!!!!!

 

As it turns out... the first half of your statement is not totally correct.
The second half is 100% correct.
It turns out that the easiest way to get an elliptical lift distribution is an elliptical planform.
However, as the aspect ratio increases to ridiculous lengths, the effect becomes
less dramatic. If a sailboat keel had a 50:1 span to chord, the added efficiency
of an elliptical planform would be less dramatic of an improvement.
You could get an elliptical distribution of lift by changing airfoil shape along the span,
but I've not seen that done.

http://www.aiaa.org/content.cfm?pageid=406&gTable=japaperimportPre97&gID=56733

http://pdf.aiaa.org/getfile.cfm?url... &urlb=!* &urlc=!*0 &urle='*BT%!@.AU

Also, in sailplanes, there is a trade of between shape and structural complexity.
A tapered wing is an approximation of an elliptical planform (compared
to constant chord).
This complexity is the reason the Spitfire was one of very few fighter planes
ever to have
an elliptical planform (as well as the fact that L/D efficiency is not really a major design
driver for a fighter plane).
In bombers it probably would have made more sense, but speed of production was more
important at the (WWII) time.
For a sailboat keel, an elliptical planform keel & rudder make a lot of sense.
Actually, it's not an elliptical planform as much as an elliptical chord distribution,
which could have a straight eading edge or trailing edge, or all sorts of
weird swept or scimitar shapes.